Effect of Deuterium Fluence on Deuterium Retention in Tungsten with Fibrous Nanostructured Layer in a Compact Plasma Device APSEDAS

The formation of helium (He) induced "fuzz layer" significantly changes the deuterium (D) retention in tungsten (W). In this study, the D retention in W with an identical fuzz layer is investigated using thermal desorption spectroscopy, with various D ion fluences. It is found that the D retention substantially decreases by similar to 80% at relatively low fluence of similar to 10(24) D/m(2), and similar to 40% at the higher fluence of 6 x 10(25) D/m(2). A new broad desorption peak at similar to 650K appearing at the higher D ion fluences of >10(25) D/m(2) originates from the interior of the fuzz layer, not the W bulk space. This suggests that the fuzz layer can force D ions to stay near the surface of W regardless of the D ion fluence, working as a diffusion barrier of hydrogen isotope fuels. (C) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research